ddnsd

Dynamic DNS Daemon

This repo hosts the code for a small dynamic DNS daemon (ddnsd) that I use to setup _acme-challenge records when issuing Let's Encrypt records for some of my personal infrastructure. It's written in Go and designed to be as small and as simple as possible. It is not a full DNS server, rather it parses DNS zonefiles and updates them. To serve your DNS zone you will need a full authoritative server; I use knot.

Host machines poke ddnsd over HTTP by making a POST request to an API endpoint during a dehydrated hook step. HTTP Basic authentication is used with credentials stored in a .htpasswd file. The username dictates the record to update which makes sure that API credentials can't be shared.

Example

Imagine your .htpasswd file contains the line test1.domain.tld.:$2y$05$DKfxz32xyO3giwz0eV1Qi.et.DL2AokHFxjYk1j78Vb7kPJCcmsyi and that your zonefile has the following contents:

domain.tld. 21600 IN SOA server.domain.tld. admin.domain.tld. 2021061800 900 300 4320000 1200
domain.tld. 21600 IN NS server.domain.tld.
test1.domain.tld. 60 IN TXT test1
test2.domain.tld. 60 IN TXT test2
test3.domain.tld. 60 IN TXT test3

After running the command curl http://test1.domain.tld.:testing@server.domain.tld:8080/update -X POST -d 'contents=__Tm_C9ZjVv8RZGi2AXLDWBey1HmTHVsS8c_A7a4hqk', your zonefile will now look like this:

domain.tld. 21600 IN SOA server.domain.tld. admin.domain.tld. 2021061800 900 300 4320000 1200
domain.tld. 21600 IN NS server.domain.tld.
test1.domain.tld. 60 IN TXT __Tm_C9ZjVv8RZGi2AXLDWBey1HmTHVsS8c_A7a4hqk
test2.domain.tld. 60 IN TXT test2
test3.domain.tld. 60 IN TXT test3

Obviously you should substitute server.domain.tld:8080 for the actual hostname and port that you are using. Make sure that you put ddnsd behind a reverse proxy which handles TLS!

Usage

Usage:
  ddnsd [flags]

Flags:
  -b, --bind string     address and port to bind to (default "localhost:8080")
  -h, --help            help for ddnsd
  -H, --hook string     full path to command/script to run after updating zonefile
  -p, --passwd string   path to .htpasswd file (default ".htpasswd")
  -z, --zone string     path to DNS zonefile (default "ddns.zone")

Installation

Pre-built binaries for a variety of operating systems and architectures are available to download from GitHub Releases. If you wish to compile from source then you will need a suitable Go toolchain installed. After that just clone the project using Git and run Make! Cross-compilation is easy in Go so by default we build for all targets and place the resulting executables in ./bin:

git clone https://github.com/CHTJonas/ddnsd.git
cd ddnsd
make clean && make all

Copyright

ddnsd is licensed under the BSD 2-Clause License.

Copyright (c) 2019–2021 Charlie Jonas.